virtual host not working for new sites.

I'm having trouble when adding new sites;
Going to the respective website invariably ends up on de default Apache "It Works!" page, instead of the virtual host folder.

I have verified the folders are being created successfuly, all the links are there.
However when i check /etc/apache2/sites-available i see that some of domains have .vhost.err files;
The respecitive .vhost and vhost.err duplicates seem to have exactly the same content.
Except for one of the new domains for which the .vhost file reads:
# Apache did not start after modifying this vhost file.
# Please check file /etc/apache2/sites-available/sportraadboutersem.be.vhost.err for syntax errors.

As far as i can tell nothing wrong here?
Some of the existing websites seemingly work flaflwessly in spite of also having a vhost.err file.
I've seen that on one of such site which has joomla installed, i can see from the folder rights status that all the sites folders are "unwriteable"
- perhaps this is relevant?

I can't pinpoint when this started happening.
The only changes we've made since everything was working was updating ISPconfig to the latest version (3.0.5.4p9 on debian), and installing an additional PHP version.
Both of these installations went without a hitch (for PHP i had to un-dos the init script, other than that no problems).

The following messages were sent to my colleague who was in holiday ...
"WARNING - Apache did not restart after the configuration change for website sportraadboutersem.be. Reverting the configuration. Saved non-working config as /etc/apache2/sites-available/sportraadboutersem.be.vhost.err"

"WARNING - Reason for Apache restart failure: Failed to get D-Bus connection: No connection to service manager."

So the actual problem lies ith the service manager, the .vhost issue is not an issue but just apache saving itself...
Subsequently restoring the .vhost files restores the afflicted websites, at least until whatever issue with the service manager occurs again the .vhost file gets adjusted again.

Right now only sportraadboutersem.be is afflicted,
however when adding a new website for testing purposes it seems to happen as well.

Running Debian 3.2.78-1,

Trying a few things with the service manager results in the following:

systemctl status
Too few arguments.

systemctl start ssh
Failed to get D-Bus connection: No connection to service manager.